HCA: Hermit Crab Association

When people build the wooden crabitats how do they seal the wood? What is safe to use for that? Someday I would like to build myself a custom crabitat so I'm researching about it.

Ideally two part epoxy - made for sealing ships, but you can also buy stuff used to seal bar tops. I used Enviro-tex Lite when I did mine, but West System and System Three are often used by vivarium and aquarium builders. It's not cheap, but the stuff lasts for years and decades! With two-part epoxy, the chemical heat reaction that occurs when it cures leaves it an inert plastic at the end. Once the smell wears off in about a week, nothing else comes off of it. It's completely non-reactive and non gassing. Mine has held up for like five years without much of a scratch. Do not leave anything with a inner corner though! If the crabs can grab on, they can pinch right through it. They took out the front corners on mine where the glass sits.

In theory, two part fiberglass resin is the same idea - chemical reaction, boom it's done, inert final product. This stuff isn't usually as thick though and takes more coats since it's made to be used with fiberglass. And you can use it with fiberglass if you want to make sure it's not going to crack in the corners or are expecting a weird weight distribution. It's what they make tubs and showers out of. Just make sure to sand it down and add a couple of top coats so there's no fibers sticking up for the crabs to grab.

What you don't ever want to use is a one-part (ie, you buy it in one container) product like water sealers, or some resins. These cure by off-gassing harmful chemicals, and they can continue to release these chemicals for years. Aside from hermits being sensitive to these things, in a sealed area it builds up even more!